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Front tyres too big...


rogerxp

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...was the excuse given to me today by a techy at Nissan.

 

Over the last couple of weeks my Zed has started to emit a rumble/grinding when on full lock at really low speeds i.e. reversing off my driveway or pulling out of my office carpark onto the road.

 

The sound/sensation soon passes and normal lunatic driving commences.

 

Was passing Westway Stockport today so nipped in to see if a techy could have a gander and offer some advice. He quickly checked the tread of the fronts and said "the tyres are too wide". I looked a little bemused so he enlightened me further. They are finding that when the tread starts to get on the low side (3mm in my case), because the fronts are so wide (the same width as the rears on a 350Z), they literally lose grip so the rumbling is the tyres just being dragged/pushed as opposed to turning the way they're pointing; kind of understeer. As soon as your increase your speed all grip returns.

 

Odd.

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Is it a low grumble or more like a thump thump thump?

 

The thumping is kind of what they are describing but its not purely because the tyres are too wide. When you turn the wheels of the car to full lock, the camber of the wheel changes such that it tilts the wheels over to extreme angles and decreases the contact patch on the road. This means the car will scrabble for grip, jumping from having grip, to no grip, to finding it again. Its a nasty sensation and completely normal in the 370z. Its because the car has big front tyres and also because they wanted to keep the turning circle smaller, and in this country with cold weather (less maluable tyres), it scrabbles on full lock. When going faster, the inertia will push the weight to the outside and correct this angle and so contact patch is right again, but slow speeds it doesnt have the weight on the contact patch.

 

Go outside and stick the car on full lock and look at the tyres, you'll see what I mean :thumbs:

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I was out in a 2 month old 370 Roadster the other day and experienced the same issues, so it looks like tyre issues still exist on the later, current models.

 

Alex. :)

Are they still running RE050's? I wonder if its the combo of steering lock and the tread pattern on RE050's that does it. Colin will be able to confirm actually as he's running the Vreds now.

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You sure this is not cold related before the tyres have warmed up? Something that surprised me during the first winter with the 370 after the previous 350's that were 'tyre noise-free' in the cold.

 

Yes, as others have said the suspension set-up at the front of the 370 does seem to provoke what I would describe as the tyres scrubbing on full lock when cold. This seems to be a feature related to the 'summer tyres' (RE050A's) fitted, but I have to say that since I have had the Sessantas fitted (also described as summer tyres) they seem to have eliminated that scrubbing type noise.

 

If you still get the noise in warmer weather or when the tyres have warmed up, then clearly something else is going on, that personally I have not experienced.

 

Oh, I should add I have an extre degree of toe-in front and rear that has certainly improved the turn-in over standard and I had that done before the tyres were changed

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